/** ***********************************************************************************
* @file         md5.c
* @brief        md5验证部分
* @details      
* @author       
* @date         2021/3
* @copyright    北京高知科技有限公司    
* @version      V1.0
* @attention    无
**************************************************************************************/

#include "md5.h"
#include <string.h>  
#include <stdio.h>  
  
//Constants for MD5Transform routine. 
#define S11 7  
#define S12 12  
#define S13 17  
#define S14 22  
#define S21 5  
#define S22 9  
#define S23 14  
#define S24 20  
#define S31 4  
#define S32 11  
#define S33 16  
#define S34 23  
#define S41 6  
#define S42 10  
#define S43 15  
#define S44 21  
  
static void MD5_memcpy(POINTER output, POINTER input, unsigned int len);  
static void MD5Transform(UINT4 state[4], unsigned char block[64]);  
static void Encode(unsigned char *output, UINT4 *input, unsigned int len);  
static void MD5_memset(POINTER output, int value, unsigned int len);  
static void Decode(UINT4 *output, unsigned char *input, unsigned int len);  
  
static unsigned char PADDING[64] = {  
    0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0  
};  
  
//F, G, H and I are basic MD5 functions. 
#define F(x, y, z)(((x) &(y)) |((~x) &(z)))  
#define G(x, y, z)(((x) &(z)) |((y) &(~z)))  
#define H(x, y, z)((x) ^(y) ^(z))  
#define I(x, y, z)((y) ^((x) |(~z)))  
  
//ROTATE_LEFT rotates x left n bits.  
#define ROTATE_LEFT(x, n)(((x) <<(n)) |((x) >>(32-(n))))  
  
//FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4. 
//Rotation is separate from addition to prevent recomputation. 
#define FF(a, b, c, d, x, s, ac) { \
   (a) += F((b),(c),(d)) +(x) +(UINT4)(ac); \
   (a) = ROTATE_LEFT((a),(s)); \
   (a) +=(b); \
    }  
#define GG(a, b, c, d, x, s, ac) { \
   (a) += G((b),(c),(d)) +(x) +(UINT4)(ac); \
   (a) = ROTATE_LEFT((a),(s)); \
   (a) +=(b); \
    }  
#define HH(a, b, c, d, x, s, ac) { \
   (a) += H((b),(c),(d)) +(x) +(UINT4)(ac); \
   (a) = ROTATE_LEFT((a),(s)); \
   (a) +=(b); \
    }  
#define II(a, b, c, d, x, s, ac) { \
   (a) += I((b),(c),(d)) +(x) +(UINT4)(ac); \
   (a) = ROTATE_LEFT((a),(s)); \
   (a) +=(b); \
    }  
  
//MD5 initialization. Begins an MD5 operation, writing a new context. 
void MD5_Init(MD5_CTX *context)/* context */  
{  
    context->count[0] = context->count[1] = 0;  
    /* Load magic initialization constants. 
    */  
    context->state[0] = 0x67452301;  
    context->state[1] = 0xefcdab89;  
    context->state[2] = 0x98badcfe;  
    context->state[3] = 0x10325476;  
}  
  
/* MD5 block update operation. Continues an MD5 message-digest 
  operation, processing another message block, and updating the 
  context. 
 */  
void MD5_Update(MD5_CTX *context, unsigned char *input, unsigned int inputLen)  
{  
    unsigned int i, index, partLen;  
  
    /* Compute number of bytes mod 64 */  
    index = (unsigned int)((context->count[0] >> 3) & 0x3F);  
  
    /* Update number of bits */  
    if((context->count[0] += ((UINT4)inputLen << 3))  
        <((UINT4)inputLen << 3))  
        context->count[1]++;  
    context->count[1] += ((UINT4)inputLen >> 29);  
  
    partLen = 64 - index;  
  
    /* Transform as many times as possible. 
    */  
    if(inputLen >= partLen) 
	{  
        MD5_memcpy((POINTER)&context->buffer[index],(POINTER)input, partLen);  
        MD5Transform(context->state, context->buffer);  
  
        for(i = partLen; i + 63 < inputLen; i += 64)  
            MD5Transform(context->state, &input[i]);  
  
        index = 0;  
    }  
    else  
        i = 0;  
  
    /* Buffer remaining input */  
    MD5_memcpy((POINTER)&context->buffer[index],(POINTER)&input[i],inputLen-i);  
}  
  
/* MD5 finalization. Ends an MD5 message-digest operation, writing the 
  the message digest and zeroizing the context. 
 */  
void MD5_Final(unsigned char digest[16], MD5_CTX *context)                                   
{  
    unsigned char bits[8];  
    unsigned int index, padLen;  
  
    /* Save number of bits */  
    Encode(bits, context->count, 8);  
  
    /* Pad out to 56 mod 64. 
    */  
    index =(unsigned int)((context->count[0] >> 3) & 0x3f);  
    padLen =(index < 56) ?(56 - index) :(120 - index);  
    MD5_Update(context, PADDING, padLen);  
  
    /* Append length(before padding) */  
    MD5_Update(context, bits, 8);  
  
    /* Store state in digest */  
    Encode(digest, context->state, 16);  
  
    /* Zeroize sensitive information. 
    */  
    MD5_memset((POINTER)context, 0, sizeof(*context));  
}  
  
/* MD5 basic transformation. Transforms state based on block. 
 */  
static void MD5Transform(UINT4 state[4], unsigned char block[64])  
{  
    UINT4 a = state[0], b = state[1], c = state[2], d = state[3], x[16];  
  
    Decode(x, block, 64);  
  
    /* Round 1 */  
    FF(a, b, c, d, x[ 0], S11, 0xd76aa478); /* 1 */  
    FF(d, a, b, c, x[ 1], S12, 0xe8c7b756); /* 2 */  
    FF(c, d, a, b, x[ 2], S13, 0x242070db); /* 3 */  
    FF(b, c, d, a, x[ 3], S14, 0xc1bdceee); /* 4 */  
    FF(a, b, c, d, x[ 4], S11, 0xf57c0faf); /* 5 */  
    FF(d, a, b, c, x[ 5], S12, 0x4787c62a); /* 6 */  
    FF(c, d, a, b, x[ 6], S13, 0xa8304613); /* 7 */  
    FF(b, c, d, a, x[ 7], S14, 0xfd469501); /* 8 */  
    FF(a, b, c, d, x[ 8], S11, 0x698098d8); /* 9 */  
    FF(d, a, b, c, x[ 9], S12, 0x8b44f7af); /* 10 */  
    FF(c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */  
    FF(b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */  
    FF(a, b, c, d, x[12], S11, 0x6b901122); /* 13 */  
    FF(d, a, b, c, x[13], S12, 0xfd987193); /* 14 */  
    FF(c, d, a, b, x[14], S13, 0xa679438e); /* 15 */  
    FF(b, c, d, a, x[15], S14, 0x49b40821); /* 16 */  
  
    /* Round 2 */  
    GG(a, b, c, d, x[ 1], S21, 0xf61e2562); /* 17 */  
    GG(d, a, b, c, x[ 6], S22, 0xc040b340); /* 18 */  
    GG(c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */  
    GG(b, c, d, a, x[ 0], S24, 0xe9b6c7aa); /* 20 */  
    GG(a, b, c, d, x[ 5], S21, 0xd62f105d); /* 21 */  
    GG(d, a, b, c, x[10], S22,  0x2441453); /* 22 */  
    GG(c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */  
    GG(b, c, d, a, x[ 4], S24, 0xe7d3fbc8); /* 24 */  
    GG(a, b, c, d, x[ 9], S21, 0x21e1cde6); /* 25 */  
    GG(d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */  
    GG(c, d, a, b, x[ 3], S23, 0xf4d50d87); /* 27 */  
    GG(b, c, d, a, x[ 8], S24, 0x455a14ed); /* 28 */  
    GG(a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */  
    GG(d, a, b, c, x[ 2], S22, 0xfcefa3f8); /* 30 */  
    GG(c, d, a, b, x[ 7], S23, 0x676f02d9); /* 31 */  
    GG(b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */  
  
    /* Round 3 */  
    HH(a, b, c, d, x[ 5], S31, 0xfffa3942); /* 33 */  
    HH(d, a, b, c, x[ 8], S32, 0x8771f681); /* 34 */  
    HH(c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */  
    HH(b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */  
    HH(a, b, c, d, x[ 1], S31, 0xa4beea44); /* 37 */  
    HH(d, a, b, c, x[ 4], S32, 0x4bdecfa9); /* 38 */  
    HH(c, d, a, b, x[ 7], S33, 0xf6bb4b60); /* 39 */  
    HH(b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */  
    HH(a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */  
    HH(d, a, b, c, x[ 0], S32, 0xeaa127fa); /* 42 */  
    HH(c, d, a, b, x[ 3], S33, 0xd4ef3085); /* 43 */  
    HH(b, c, d, a, x[ 6], S34,  0x4881d05); /* 44 */  
    HH(a, b, c, d, x[ 9], S31, 0xd9d4d039); /* 45 */  
    HH(d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */  
    HH(c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */  
    HH(b, c, d, a, x[ 2], S34, 0xc4ac5665); /* 48 */  
  
    /* Round 4 */  
    II(a, b, c, d, x[ 0], S41, 0xf4292244); /* 49 */  
    II(d, a, b, c, x[ 7], S42, 0x432aff97); /* 50 */  
    II(c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */  
    II(b, c, d, a, x[ 5], S44, 0xfc93a039); /* 52 */  
    II(a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */  
    II(d, a, b, c, x[ 3], S42, 0x8f0ccc92); /* 54 */  
    II(c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */  
    II(b, c, d, a, x[ 1], S44, 0x85845dd1); /* 56 */  
    II(a, b, c, d, x[ 8], S41, 0x6fa87e4f); /* 57 */  
    II(d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */  
    II(c, d, a, b, x[ 6], S43, 0xa3014314); /* 59 */  
    II(b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */  
    II(a, b, c, d, x[ 4], S41, 0xf7537e82); /* 61 */  
    II(d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */  
    II(c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /* 63 */  
    II(b, c, d, a, x[ 9], S44, 0xeb86d391); /* 64 */  
  
    state[0] += a;  
    state[1] += b;  
    state[2] += c;  
    state[3] += d;  
  
    /* Zeroize sensitive information. 
    */  
    MD5_memset((POINTER)x, 0, sizeof(x));  
}  
  
/* Encodes input(UINT4) into output(unsigned char). Assumes len is 
  a multiple of 4. 
 */  
static void Encode(unsigned char *output, UINT4 *input, unsigned int len)  
{  
    unsigned int i, j;  
  
    for(i = 0, j = 0; j < len; i++, j += 4) 
	{  
        output[j] =(unsigned char)(input[i] & 0xff);  
        output[j+1] =(unsigned char)((input[i] >> 8) & 0xff);  
        output[j+2] =(unsigned char)((input[i] >> 16) & 0xff);  
        output[j+3] =(unsigned char)((input[i] >> 24) & 0xff);  
    }  
}  
  
/* Decodes input(unsigned char) into output(UINT4). Assumes len is 
  a multiple of 4. 
 */  
static void Decode(UINT4 *output, unsigned char *input, unsigned int len)  
{  
    unsigned int i, j;  
  
    for(i = 0, j = 0; j < len; i++, j += 4)  
        output[i] =((UINT4)input[j]) |(((UINT4)input[j+1]) << 8) |  
       (((UINT4)input[j+2]) << 16) |(((UINT4)input[j+3]) << 24);  
}  
  
/* Note: Replace "for loop" with standard memcpy if possible. 
 */  
  
static void MD5_memcpy(POINTER output, POINTER input, unsigned int len)  
{  
    unsigned int i;  
  
    for(i = 0; i < len; i++)  
        output[i] = input[i];  
}  
  
/* Note: Replace "for loop" with standard memset if possible. 
 */  
static void MD5_memset(POINTER output, int value, unsigned int len)  
{  
    unsigned int i;  
  
    for(i = 0; i < len; i++)  
       ((char *)output)[i] = (char)value;  
}

/* Digests a string and prints the result. 
 */  
void MD5_String(unsigned char digest[16],char *string)
{  
    MD5_CTX context;  
    unsigned int len = strlen(string);  
  
    MD5_Init(&context);  
    MD5_Update(&context,(unsigned char *)string, len);  
    MD5_Final(digest, &context);  
}  
